The present invention pertains to a method for stabilizing the hydrolyzable chlorine content of glycidyl ethers.
In the electronics industry, epoxy resins are employed as encapsulating compounds, potting compounds, electrical laminates and the like. The electronics industry desires to employ epoxy resins which are low in hydrolyzable chloride content because their presence tends to reduce the electrical properties and reliability of the ultimate products. Most processes for producing epoxy resins of the glycidyl ether type involve reacting a hydroxyl-containing material with an epihalohydrin to form a halohydrin ether intermediate product. This product is then dehydrohalogenated with an alkali metal hydroxide in the presence of one or more organic solvents. The resultant product is then washed with water and the resultant organic phase is distilled to remove the organic solvent(s). This process usually produces a product low in hydrolyzable halide content. However, when the epoxy resin contains as little as 2 ppm of alkali metal base, the hydrolyzable halide content increases when subjected to heat for prolonged periods of time.
This is highly undesirable. The present invention provides a method for stabilizing the hydrolyzable halide content of an epoxy resin which contains residual quantities of alkali metal base.